1. Technical Field
The present invention is related to a supplemental cooling system for cooling with ambient air a mechanically refrigerated container or "cold box". More specifically, the supplemental cooling system is alternatively used to cool the box in place of the independently operated mechanical refrigeration system.
2. Prior Art
Supplemental cooling systems which use cool ambient air, when available, to cool a refrigerated box instead of using the refrigeration system are known in the prior art. Supplemental cooling systems are able to significantly reduce the amount of energy required to cool an enclosure. However, several problems have been encountered in the use of prior art supplemental cooling systems.
One problem with prior art systems is the need to interface the supplemental cooling system with the normal refrigeration equipment. Such interfacing generally requires wiring the supplemental system to the refrigeration equipment so that the refrigeration equipment does not operate while cool air is available to the supplemental cooling system. When prior art supplemental cooling systems are retrofitted to preexisting refrigeration systems, problems are often encountered due to the need to interface with many different types of refrigeration equipment. This is time consuming and requires analysis of the refrigeration system electrical controls. If the wiring is incorrectly performed the refrigeration equipment can be adversely affected which could result in damage to the refrigerated products or the refrigeration system.
Another problem that has faced prior art supplemental cooling systems is the accumulation of condensation in the system when it is not in use. Condensation is undesirable since it facilitates the formation of mildew and bacteria which is not acceptable in cold storage facilities where sanitation is important. Condensation is formed when cool refrigerated air on one side of a vent or valve cools the vent or valve and warm humid ambient air contacts the other side of the vent or valve causing the moisture in the ambient air to condense on the cool surface.
Another problem with prior art supplemental cooling systems is that they do not adequately prevent particulate matter, dirt and debris from being drawn into the enclosure with the cool air. In particular, fine particulate matter or smoke have not been removed or detected by prior art systems.
In prior cooling systems insects and rodents have been either pulled into the intake or have crept into the intake or exhaust vents. Supplemental cooling systems require direct venting from the exterior of a building to the cold storage enclosure. The vents of prior supplemental cooling systems provide avenues of entry to the cold storage enclosure for such life forms. This problem precluded the use of auxiliary cooling systems in many sanitary installations.